drivers/pwm/pwm-cros-ec.c - linux - Git at Google

 // SPDX-License-Identifier: GPL-2.0
 /*
  * Expose a PWM controlled by the ChromeOS EC to the host processor.
  *
  * Copyright (C) 2016 Google, Inc.
  */

 #include <linux/module.h>
 #include <linux/platform_data/cros_ec_commands.h>
 #include <linux/platform_data/cros_ec_proto.h>
 #include <linux/platform_device.h>
 #include <linux/pwm.h>
 #include <linux/slab.h>

 /**
  * struct cros_ec_pwm_device - Driver data for EC PWM
  *
  * @dev: Device node
  * @ec: Pointer to EC device
  * @chip: PWM controller chip
  */
 struct cros_ec_pwm_device {
 	struct device *dev;
 	struct cros_ec_device *ec;
 	struct pwm_chip chip;
 };

 /**
  * struct cros_ec_pwm - per-PWM driver data
  * @duty_cycle: cached duty cycle
  */
 struct cros_ec_pwm {
 	u16 duty_cycle;
 };

 static inline struct cros_ec_pwm_device *pwm_to_cros_ec_pwm(struct pwm_chip *c)
 {
 	return container_of(c, struct cros_ec_pwm_device, chip);
 }

 static int cros_ec_pwm_request(struct pwm_chip *chip, struct pwm_device *pwm)
 {
 	struct cros_ec_pwm *channel;

 	channel = kzalloc(sizeof(*channel), GFP_KERNEL);
 	if (!channel)
 		return -ENOMEM;

 	pwm_set_chip_data(pwm, channel);

 	return 0;
 }

 static void cros_ec_pwm_free(struct pwm_chip *chip, struct pwm_device *pwm)
 {
 	struct cros_ec_pwm *channel = pwm_get_chip_data(pwm);

 	kfree(channel);
 }

 static int cros_ec_pwm_set_duty(struct cros_ec_device *ec, u8 index, u16 duty)
 {
 	struct {
 		struct cros_ec_command msg;
 		struct ec_params_pwm_set_duty params;
 	} __packed buf;
 	struct ec_params_pwm_set_duty *params = &buf.params;
 	struct cros_ec_command *msg = &buf.msg;

 	memset(&buf, 0, sizeof(buf));

 	msg->version = 0;
 	msg->command = EC_CMD_PWM_SET_DUTY;
 	msg->insize = 0;
 	msg->outsize = sizeof(*params);

 	params->duty = duty;
 	params->pwm_type = EC_PWM_TYPE_GENERIC;
 	params->index = index;

 	return cros_ec_cmd_xfer_status(ec, msg);
 }

 static int cros_ec_pwm_get_duty(struct cros_ec_device *ec, u8 index)
 {
 	struct {
 		struct cros_ec_command msg;
 		union {
 			struct ec_params_pwm_get_duty params;
 			struct ec_response_pwm_get_duty resp;
 		};
 	} __packed buf;
 	struct ec_params_pwm_get_duty *params = &buf.params;
 	struct ec_response_pwm_get_duty *resp = &buf.resp;
 	struct cros_ec_command *msg = &buf.msg;
 	int ret;

 	memset(&buf, 0, sizeof(buf));

 	msg->version = 0;
 	msg->command = EC_CMD_PWM_GET_DUTY;
 	msg->insize = sizeof(*resp);
 	msg->outsize = sizeof(*params);

 	params->pwm_type = EC_PWM_TYPE_GENERIC;
 	params->index = index;

 	ret = cros_ec_cmd_xfer_status(ec, msg);
 	if (ret < 0)
 		return ret;

 	return resp->duty;
 }

 static int cros_ec_pwm_apply(struct pwm_chip *chip, struct pwm_device *pwm,
 			     const struct pwm_state *state)
 {
 	struct cros_ec_pwm_device *ec_pwm = pwm_to_cros_ec_pwm(chip);
 	struct cros_ec_pwm *channel = pwm_get_chip_data(pwm);
 	u16 duty_cycle;
 	int ret;

 	/* The EC won't let us change the period */
 	if (state->period != EC_PWM_MAX_DUTY)
 		return -EINVAL;

 	if (state->polarity != PWM_POLARITY_NORMAL)
 		return -EINVAL;

 	/*
 	 * EC doesn't separate the concept of duty cycle and enabled, but
 	 * kernel does. Translate.
 	 */
 	duty_cycle = state->enabled ? state->duty_cycle : 0;

 	ret = cros_ec_pwm_set_duty(ec_pwm->ec, pwm->hwpwm, duty_cycle);
 	if (ret < 0)
 		return ret;

 	channel->duty_cycle = state->duty_cycle;

 	return 0;
 }

 static void cros_ec_pwm_get_state(struct pwm_chip *chip, struct pwm_device *pwm,
 				  struct pwm_state *state)
 {
 	struct cros_ec_pwm_device *ec_pwm = pwm_to_cros_ec_pwm(chip);
 	struct cros_ec_pwm *channel = pwm_get_chip_data(pwm);
 	int ret;

 	ret = cros_ec_pwm_get_duty(ec_pwm->ec, pwm->hwpwm);
 	if (ret < 0) {
 		dev_err(chip->dev, "error getting initial duty: %d\n", ret);
 		return;
 	}

 	state->enabled = (ret > 0);
 	state->period = EC_PWM_MAX_DUTY;

 	/*
 	 * Note that "disabled" and "duty cycle == 0" are treated the same. If
 	 * the cached duty cycle is not zero, used the cached duty cycle. This
 	 * ensures that the configured duty cycle is kept across a disable and
 	 * enable operation and avoids potentially confusing consumers.
 	 *
 	 * For the case of the initial hardware readout, channel->duty_cycle
 	 * will be 0 and the actual duty cycle read from the EC is used.
 	 */
 	if (ret == 0 && channel->duty_cycle > 0)
 		state->duty_cycle = channel->duty_cycle;
 	else
 		state->duty_cycle = ret;
 }

 static struct pwm_device *
 cros_ec_pwm_xlate(struct pwm_chip *pc, const struct of_phandle_args *args)
 {
 	struct pwm_device *pwm;

 	if (args->args[0] >= pc->npwm)
 		return ERR_PTR(-EINVAL);

 	pwm = pwm_request_from_chip(pc, args->args[0], NULL);
 	if (IS_ERR(pwm))
 		return pwm;

 	/* The EC won't let us change the period */
 	pwm->args.period = EC_PWM_MAX_DUTY;

 	return pwm;
 }

 static const struct pwm_ops cros_ec_pwm_ops = {
 	.request = cros_ec_pwm_request,
 	.free = cros_ec_pwm_free,
 	.get_state	= cros_ec_pwm_get_state,
 	.apply		= cros_ec_pwm_apply,
 	.owner		= THIS_MODULE,
 };

 /*
  * Determine the number of supported PWMs. The EC does not return the number
  * of PWMs it supports directly, so we have to read the pwm duty cycle for
  * subsequent channels until we get an error.
  */
 static int cros_ec_num_pwms(struct cros_ec_device *ec)
 {
 	int i, ret;

 	/* The index field is only 8 bits */
 	for (i = 0; i <= U8_MAX; i++) {
 		ret = cros_ec_pwm_get_duty(ec, i);
 		/*
 		 * We look for SUCCESS, INVALID_COMMAND, or INVALID_PARAM
 		 * responses; everything else is treated as an error.
 		 * The EC error codes map to -EOPNOTSUPP and -EINVAL,
 		 * so check for those.
 		 */
 		switch (ret) {
 		case -EOPNOTSUPP:	/* invalid command */
 			return -ENODEV;
 		case -EINVAL:		/* invalid parameter */
 			return i;
 		default:
 			if (ret < 0)
 				return ret;
 			break;
 		}
 	}

 	return U8_MAX;
 }

 static int cros_ec_pwm_probe(struct platform_device *pdev)
 {
 	struct cros_ec_device *ec = dev_get_drvdata(pdev->dev.parent);
 	struct device *dev = &pdev->dev;
 	struct cros_ec_pwm_device *ec_pwm;
 	struct pwm_chip *chip;
 	int ret;

 	if (!ec) {
 		dev_err(dev, "no parent EC device\n");
 		return -EINVAL;
 	}

 	ec_pwm = devm_kzalloc(dev, sizeof(*ec_pwm), GFP_KERNEL);
 	if (!ec_pwm)
 		return -ENOMEM;
 	chip = &ec_pwm->chip;
 	ec_pwm->ec = ec;

 	/* PWM chip */
 	chip->dev = dev;
 	chip->ops = &cros_ec_pwm_ops;
 	chip->of_xlate = cros_ec_pwm_xlate;
 	chip->of_pwm_n_cells = 1;
 	ret = cros_ec_num_pwms(ec);
 	if (ret < 0) {
 		dev_err(dev, "Couldn't find PWMs: %d\n", ret);
 		return ret;
 	}
 	chip->npwm = ret;
 	dev_dbg(dev, "Probed %u PWMs\n", chip->npwm);

 	ret = pwmchip_add(chip);
 	if (ret < 0) {
 		dev_err(dev, "cannot register PWM: %d\n", ret);
 		return ret;
 	}

 	platform_set_drvdata(pdev, ec_pwm);

 	return ret;
 }

 static int cros_ec_pwm_remove(struct platform_device *dev)
 {
 	struct cros_ec_pwm_device *ec_pwm = platform_get_drvdata(dev);
 	struct pwm_chip *chip = &ec_pwm->chip;

 	return pwmchip_remove(chip);
 }

 #ifdef CONFIG_OF
 static const struct of_device_id cros_ec_pwm_of_match[] = {
 	{ .compatible = "google,cros-ec-pwm" },
 	{},
 };
 MODULE_DEVICE_TABLE(of, cros_ec_pwm_of_match);
 #endif

 static struct platform_driver cros_ec_pwm_driver = {
 	.probe = cros_ec_pwm_probe,
 	.remove = cros_ec_pwm_remove,
 	.driver = {
 		.name = "cros-ec-pwm",
 		.of_match_table = of_match_ptr(cros_ec_pwm_of_match),
 	},
 };
 module_platform_driver(cros_ec_pwm_driver);

 MODULE_ALIAS("platform:cros-ec-pwm");
 MODULE_DESCRIPTION("ChromeOS EC PWM driver");
 MODULE_LICENSE("GPL v2");
	// SPDX-License-Identifier: GPL-2.0
	/*
	* Expose a PWM controlled by the ChromeOS EC to the host processor.
	*
	* Copyright (C) 2016 Google, Inc.
	*/

	#include <linux/module.h>
	#include <linux/platform_data/cros_ec_commands.h>
	#include <linux/platform_data/cros_ec_proto.h>
	#include <linux/platform_device.h>
	#include <linux/pwm.h>
	#include <linux/slab.h>

	/**
	* struct cros_ec_pwm_device - Driver data for EC PWM
	*
	* @dev: Device node
	* @ec: Pointer to EC device
	* @chip: PWM controller chip
	*/
	struct cros_ec_pwm_device {
	struct device *dev;
	struct cros_ec_device *ec;
	struct pwm_chip chip;
	};

	/**
	* struct cros_ec_pwm - per-PWM driver data
	* @duty_cycle: cached duty cycle
	*/
	struct cros_ec_pwm {
	u16 duty_cycle;
	};

	static inline struct cros_ec_pwm_device pwm_to_cros_ec_pwm(struct pwm_chip c)
	{
	return container_of(c, struct cros_ec_pwm_device, chip);
	}

	static int cros_ec_pwm_request(struct pwm_chip chip, struct pwm_device pwm)
	{
	struct cros_ec_pwm *channel;

	channel = kzalloc(sizeof(*channel), GFP_KERNEL);
	if (!channel)
	return -ENOMEM;

	pwm_set_chip_data(pwm, channel);

	return 0;
	}

	static void cros_ec_pwm_free(struct pwm_chip chip, struct pwm_device pwm)
	{
	struct cros_ec_pwm *channel = pwm_get_chip_data(pwm);

	kfree(channel);
	}

	static int cros_ec_pwm_set_duty(struct cros_ec_device *ec, u8 index, u16 duty)
	{
	struct {
	struct cros_ec_command msg;
	struct ec_params_pwm_set_duty params;
	} __packed buf;
	struct ec_params_pwm_set_duty *params = &buf.params;
	struct cros_ec_command *msg = &buf.msg;

	memset(&buf, 0, sizeof(buf));

	msg->version = 0;
	msg->command = EC_CMD_PWM_SET_DUTY;
	msg->insize = 0;
	msg->outsize = sizeof(*params);

	params->duty = duty;
	params->pwm_type = EC_PWM_TYPE_GENERIC;
	params->index = index;

	return cros_ec_cmd_xfer_status(ec, msg);
	}

	static int cros_ec_pwm_get_duty(struct cros_ec_device *ec, u8 index)
	{
	struct {
	struct cros_ec_command msg;
	union {
	struct ec_params_pwm_get_duty params;
	struct ec_response_pwm_get_duty resp;
	};
	} __packed buf;
	struct ec_params_pwm_get_duty *params = &buf.params;
	struct ec_response_pwm_get_duty *resp = &buf.resp;
	struct cros_ec_command *msg = &buf.msg;
	int ret;

	memset(&buf, 0, sizeof(buf));

	msg->version = 0;
	msg->command = EC_CMD_PWM_GET_DUTY;
	msg->insize = sizeof(*resp);
	msg->outsize = sizeof(*params);

	params->pwm_type = EC_PWM_TYPE_GENERIC;
	params->index = index;

	ret = cros_ec_cmd_xfer_status(ec, msg);
	if (ret < 0)
	return ret;

	return resp->duty;
	}

	static int cros_ec_pwm_apply(struct pwm_chip chip, struct pwm_device pwm,
	const struct pwm_state *state)
	{
	struct cros_ec_pwm_device *ec_pwm = pwm_to_cros_ec_pwm(chip);
	struct cros_ec_pwm *channel = pwm_get_chip_data(pwm);
	u16 duty_cycle;
	int ret;

	/* The EC won't let us change the period */
	if (state->period != EC_PWM_MAX_DUTY)
	return -EINVAL;

	if (state->polarity != PWM_POLARITY_NORMAL)
	return -EINVAL;

	/*
	* EC doesn't separate the concept of duty cycle and enabled, but
	* kernel does. Translate.
	*/
	duty_cycle = state->enabled ? state->duty_cycle : 0;

	ret = cros_ec_pwm_set_duty(ec_pwm->ec, pwm->hwpwm, duty_cycle);
	if (ret < 0)
	return ret;

	channel->duty_cycle = state->duty_cycle;

	return 0;
	}

	static void cros_ec_pwm_get_state(struct pwm_chip chip, struct pwm_device pwm,
	struct pwm_state *state)
	{
	struct cros_ec_pwm_device *ec_pwm = pwm_to_cros_ec_pwm(chip);
	struct cros_ec_pwm *channel = pwm_get_chip_data(pwm);
	int ret;

	ret = cros_ec_pwm_get_duty(ec_pwm->ec, pwm->hwpwm);
	if (ret < 0) {
	dev_err(chip->dev, "error getting initial duty: %d\n", ret);
	return;
	}

	state->enabled = (ret > 0);
	state->period = EC_PWM_MAX_DUTY;

	/*
	* Note that "disabled" and "duty cycle == 0" are treated the same. If
	* the cached duty cycle is not zero, used the cached duty cycle. This
	* ensures that the configured duty cycle is kept across a disable and
	* enable operation and avoids potentially confusing consumers.
	*
	* For the case of the initial hardware readout, channel->duty_cycle
	* will be 0 and the actual duty cycle read from the EC is used.
	*/
	if (ret == 0 && channel->duty_cycle > 0)
	state->duty_cycle = channel->duty_cycle;
	else
	state->duty_cycle = ret;
	}

	static struct pwm_device *
	cros_ec_pwm_xlate(struct pwm_chip pc, const struct of_phandle_args args)
	{
	struct pwm_device *pwm;

	if (args->args[0] >= pc->npwm)
	return ERR_PTR(-EINVAL);

	pwm = pwm_request_from_chip(pc, args->args[0], NULL);
	if (IS_ERR(pwm))
	return pwm;

	/* The EC won't let us change the period */
	pwm->args.period = EC_PWM_MAX_DUTY;

	return pwm;
	}

	static const struct pwm_ops cros_ec_pwm_ops = {
	.request = cros_ec_pwm_request,
	.free = cros_ec_pwm_free,
	.get_state = cros_ec_pwm_get_state,
	.apply = cros_ec_pwm_apply,
	.owner = THIS_MODULE,
	};

	/*
	* Determine the number of supported PWMs. The EC does not return the number
	* of PWMs it supports directly, so we have to read the pwm duty cycle for
	* subsequent channels until we get an error.
	*/
	static int cros_ec_num_pwms(struct cros_ec_device *ec)
	{
	int i, ret;

	/* The index field is only 8 bits */
	for (i = 0; i <= U8_MAX; i++) {
	ret = cros_ec_pwm_get_duty(ec, i);
	/*
	* We look for SUCCESS, INVALID_COMMAND, or INVALID_PARAM
	* responses; everything else is treated as an error.
	* The EC error codes map to -EOPNOTSUPP and -EINVAL,
	* so check for those.
	*/
	switch (ret) {
	case -EOPNOTSUPP: /* invalid command */
	return -ENODEV;
	case -EINVAL: /* invalid parameter */
	return i;
	default:
	if (ret < 0)
	return ret;
	break;
	}
	}

	return U8_MAX;
	}

	static int cros_ec_pwm_probe(struct platform_device *pdev)
	{
	struct cros_ec_device *ec = dev_get_drvdata(pdev->dev.parent);
	struct device *dev = &pdev->dev;
	struct cros_ec_pwm_device *ec_pwm;
	struct pwm_chip *chip;
	int ret;

	if (!ec) {
	dev_err(dev, "no parent EC device\n");
	return -EINVAL;
	}

	ec_pwm = devm_kzalloc(dev, sizeof(*ec_pwm), GFP_KERNEL);
	if (!ec_pwm)
	return -ENOMEM;
	chip = &ec_pwm->chip;
	ec_pwm->ec = ec;

	/* PWM chip */
	chip->dev = dev;
	chip->ops = &cros_ec_pwm_ops;
	chip->of_xlate = cros_ec_pwm_xlate;
	chip->of_pwm_n_cells = 1;
	ret = cros_ec_num_pwms(ec);
	if (ret < 0) {
	dev_err(dev, "Couldn't find PWMs: %d\n", ret);
	return ret;
	}
	chip->npwm = ret;
	dev_dbg(dev, "Probed %u PWMs\n", chip->npwm);

	ret = pwmchip_add(chip);
	if (ret < 0) {
	dev_err(dev, "cannot register PWM: %d\n", ret);
	return ret;
	}

	platform_set_drvdata(pdev, ec_pwm);

	return ret;
	}

	static int cros_ec_pwm_remove(struct platform_device *dev)
	{
	struct cros_ec_pwm_device *ec_pwm = platform_get_drvdata(dev);
	struct pwm_chip *chip = &ec_pwm->chip;

	return pwmchip_remove(chip);
	}

	#ifdef CONFIG_OF
	static const struct of_device_id cros_ec_pwm_of_match[] = {
	{ .compatible = "google,cros-ec-pwm" },
	{},
	};
	MODULE_DEVICE_TABLE(of, cros_ec_pwm_of_match);
	#endif

	static struct platform_driver cros_ec_pwm_driver = {
	.probe = cros_ec_pwm_probe,
	.remove = cros_ec_pwm_remove,
	.driver = {
	.name = "cros-ec-pwm",
	.of_match_table = of_match_ptr(cros_ec_pwm_of_match),
	},
	};
	module_platform_driver(cros_ec_pwm_driver);

	MODULE_ALIAS("platform:cros-ec-pwm");
	MODULE_DESCRIPTION("ChromeOS EC PWM driver");
	MODULE_LICENSE("GPL v2");